Multi-element hybrid perforating apparatus

ABSTRACT

A perforating apparatus includes a carrier, explosive devices mounted to the carrier, energetic cells arranged among the explosive devices, and a sleeve to receive at least a portion of the carrier, where the sleeve is formed of an energetic material.

BACKGROUND

To complete a well for purposes of producing fluids (such as hydrocarbons or other fluids) from a reservoir, or injecting fluids into the reservoir, one or more zones in the well are perforated to allow for fluid communication between a wellbore and the reservoir. Perforation is accomplished by lowering a perforating gun to a target interval within the well. Activation of the perforating gun creates openings in any surrounding casing or liner and extends perforation tunnels into the surrounding subterranean formation.

SUMMARY

In general, according to some implementations, a perforating apparatus includes a carrier, explosive devices mounted to the carrier, energetic cells arranged among the explosive devices, and a sleeve to receive at least a portion of the carrier, where the sleeve is formed of an energetic material.

Other or alternative features will become apparent from the following description, from the drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments are described with respect to the following figures:

FIG. 1 illustrates an example tool string having a perforating gun configured according to some implementations;

FIG. 2 is a partial sectional view of a perforating gun according to some implementations;

FIGS. 3 and 4 illustrate modular energetic sleeves according to some implementations;

FIGS. 5 and 6 illustrate components of a perforator charge according to further implementations; and

FIG. 7 is a flow diagram of a process of forming a perforating gun according to some implementations.

DETAILED DESCRIPTION

To form perforations in a well (perforations are formed in a surrounding formation as well as in any casing or liner that lines the well), a perforating apparatus can be deployed into the well. An example of a perforating apparatus is a perforating gun that carries explosive devices that when detonated produces explosive jets that extend the perforations into a surrounding formation (in any intermediate casing or liner). Such explosive devices are referred to as perforator charges, and in some cases, are referred to as shaped charges.

The explosive nature of creating perforation tunnels in the subterranean formation can create a crushed zone in the formation. A “crushed zone” refers to a damaged zone that surrounds a perforation tunnel, where the perforating action has altered the formation structure and its permeability. Also, the perforating action can cause debris to fill perforation tunnels. The crushed zone damage can result in reduced ability to perform production or injection.

In accordance with some embodiments, a perforating apparatus, such as a perforating gun, is provided that includes various components formed of an energetic material that are able to produce a relatively high energy wave (or waves), such as in the form of a relatively high pressure pulse or pressure pulses. The high energy wave can result in creation of fractures in the subterranean formation, enlargement of a perforation tunnel, and/or removal or reduction of crushed zone damage in the formation. The components formed of the energetic material is activated in response to detonation of the explosive devices (such as perforator charges) in the perforating apparatus.

In some implementations, the deployment of multiple components of an energetic material allows for creation of multiple energy waves (such as multiple pressure pulses). In some implementations, the multiple components formed of an energetic material can include some combination of the following: a charge formed of an energetic material provided in a section of a perforating apparatus that is connected (above or below) to the section of the perforating apparatus that includes the explosive devices; energetic cells (formed of an energetic material) arranged among the explosive devices; a modular energetic sleeve formed around an outer surface of a carrier mounted above the explosive devices, where the carrier can include a loading tube or other type of carrier; a sleeve formed of an energetic material that is provided around an outer housing of the perforating apparatus; and a member formed of an energetic material formed as part of an individual explosive device, such as a perforator charge.

Examples of an energetic material can include any one or more of the following: a propellant, a high explosive, a gun powder, a combustible metallic powder, thermite, or any combination thereof.

In the ensuing discussion, reference is made to a carrier (to which explosive devices are mounted) that is in the form of a loading tube. Also, reference is made to perforator charges, which are a form of explosive devices. Additionally, reference is made to an energetic material that includes a propellant. Although reference is made to the foregoing example implementations, note that other example components can be employed in other embodiments.

FIG. 1 illustrates a tool string 100 that is lowered into a wellbore 102. The wellbore 102 can be lined with casing or liner 104. The tool string 100 is lowered on a deployment structure 106, which can be a wireline, tubing (e.g. coiled tubing or other tubing), a pipe, and so forth. The tool string 100 has a perforating gun 108, which includes a carrier structure 110 to which perforator charges 112 are attached. In some implementations, the carrier structure 110 can be a loading tube defining an inner chamber (which can be sealed from outside well fluids) in which the perforator charges 112 are mounted. Alternatively, the carrier structure 110 can be a strip onto which the perforator charges 112 are mounted. In other examples, the carrier structure 110 can have other forms.

The perforator charges 112 are ballistically connected to a detonating cord 114. Initiation of the detonating cord 114 causes detonation of the perforator charges 112.

The detonating cord 114 can be connected to a firing head 116, which can be activated from an earth surface 118, such as by use of equipment at the earth surface 118. The activation of the firing head 116 can be in response to electrical commands, acoustic commands, pressure commands, optical commands, and so forth, that can be sent from the equipment at the earth surface 118 to the firing head 116. In other examples, the activation of the firing head 116 can be performed mechanically.

FIG. 2 is a partial sectional view of an example perforating gun 108 that has multiple sections 202, 204, and 206. Portions of the perforating gun 108 are cut away to illustrate inner components. The upper gun section 202 and intermediate gun section 204 are interconnected by an adapter 208, and the intermediate gun section 204 and lower gun section 206 are interconnected by an adapter 210. The intermediate gun section 204 includes the loading tube 110, perforator charges 112, and detonating cord 114 discussed above in connection with FIG. 1.

The upper gun section 202 includes a propellant charge 212, which is formed of a propellant (or other energetic material). The propellant charge 212 is contained inside an outer housing 228 of the upper gun section 202 Similarly, the lower gun section 206 includes a propellant charge 214, which includes a propellant or other energetic material. The propellant charge 214 is contained inside an outer housing 230 of the lower gun section 206.

The upper gun section 202 has a gun head 216 to allow the perforating gun 108 to connect to another portion of the tool string 100 shown in FIG. 1. The lower gun section 206 has a bottom nose piece 218.

The intermediate gun section 204 also includes various components formed of a propellant or other energetic material. In some examples, as shown in FIG. 2, propellant cells 220 are arranged among the perforator charges 112. Each propellant cell 220 is formed of a propellant or other energetic material. In addition, as shown in FIG. 2, a modular propellant sleeve 222 is provided around an outer surface of the loading tube 110. A sleeve provided around the loading tube (or other carrier) can refer to a sleeve that either partially or fully surrounds the outer surface of the loading tube or other carrier.

The loading tube 110 is positioned inside an outer housing 224 of the intermediate gun section 204. In some examples, another outer propellant sleeve 226 can be provided around the outer surface of the outer gun housing 224 of the intermediate gun section 204. The outer propellant sleeve 226 can also include a propellant or other energetic material.

As further shown in FIG. 2, a sealed central passageway 234 (sealed from fluids outside the central passageway 234) is provided in the upper gun section 202 through the propellant charge 212. The detonating cord 114 for activating the perforator charges 112 can be passed through the central passageway 234 in the upper gun section 202. The detonating cord 114 extends from the gun head 216 through the central passageway 234 to the intermediate gun section 204.

The detonating cord 114 further extends from the intermediate gun section 204 to the lower gun section 206. The lower gun section 206 includes a central passageway 236 that extends through the perforator charge 214. The detonating cord 114 extends inside the central passageway 236.

In operation, an activation signal (e.g. electrical signal, acoustic signal, optical signal, hydraulic signal, mechanical stimulus, etc.) can be provided to the gun head 216. In some examples, the gun head 216 can include a firing mechanism that can initiate the detonating cord 114. Initiation of the detonating cord 114 causes an initiation wave to travel down the detonating cord 114.

Initiation of the portion of the detonating cord 114 in the central passageway 234 in the upper gun section 202 causes activation of the propellant charge 212. A pressure wave caused by the activation of the propellant charge 212 travels through openings 238 in the outer housing 228 of the upper gun section 202.

The initiation wave continues to travel along the detonating cord 114 until it reaches the intermediate gun section 204. Initiation of the portion of the detonating cord 114 in the intermediate gun section 204 causes detonation of the perforator charges 112, which in turn causes activation of the propellant cells 220, the modular propellant sleeve 222, and the outer propellant sleeve 226. Activation of the propellant cells 220, the modular propellant sleeve 222, and the outer propellant sleeve 226 causes resultant pressure waves to be generated, which can be propagated through openings in the outer housing 224 of the intermediate gun section 204. Such openings in the outer housing 224 are produced by perforating jets generated by the detonated perforator charges 112.

The initiation wave continues to travel down the detonating cord 114 to the lower gun section 206. Initiation of the detonating cord 114 in the central passageway 236 of the lower gun section 206 causes activation of the propellant charge 214, which causes the resultant pressure wave to travel through openings 240 in the outer housing 230 of the lower gun section 206.

Although a specific example of the perforating gun 108 is shown in FIG. 2, note that in other examples, some of the elements depicted in FIG. 2 can be omitted. For example, the outer propellant charge 226 can be omitted in some implementations. As another example, the propellant cells 220 can be omitted in some implementations. As yet another example, the propellant charge 212 and/or propellant charge 214 in the upper and lower gun sections 202 and 206, respectively, can be omitted.

More generally, different configurations of the perforating gun 108 can include different combinations of the following propellant elements: propellant charge 212, propellant charge 214, propellant cells 220, modular propellant sleeve 222, and outer propellant sleeve 226.

As discussed further below, in other implementations, the perforator charges 112 can be incorporated with a propellant or other energetic material. Such propellant or other energetic material incorporated into a perforator charge 112 can be used in addition to or in place of any or some combination of the foregoing propellant elements.

FIG. 3 shows an example configuration of the modular propellant sleeve 222. In examples according to FIG. 3, the modular propellant sleeve 222 includes a tubular structure 300 that has openings 302 that correspond to positions of the perforator charges 112 in the loading tube 110 of FIG. 2. These openings 302 of the propellant sleeve 222 are positioned such that the perforating jet of each perforator charge 112 extends through the corresponding opening 302 of the propellant sleeve 222. A tubular structure can refer to a structure as generally cylindrical, or that can have different cross-sectional shapes, such as a rectangular shape, or some other shape.

In addition to the openings 302, the tubular structure 300 of the propellant sleeve 222 also includes grooves 304 that interconnect adjacent openings 302. These grooves 304 are arranged to receive the detonating cord 114. In some examples, the grooves 304 are arranged along a spiral path to allow the detonating cord 114 to be arranged in a spiral pattern around the perforator charges 112.

FIG. 4 illustrates a different configuration of the modular propellant sleeve 222. In FIG. 4, the modular propellant sleeve 222 includes a tubular structure 400 that has respective openings 402 corresponding to positions of the perforator charges 112 in the loading tube 110. However, in the configuration of FIG. 4, grooves (such as grooves 304 in FIG. 3) are not provided for interconnecting the openings of 402. Instead, the detonating cord 114 can be arranged along the outer surface of the tubular structure 400.

FIG. 5 is a cross-sectional view of an example perforator charge 112 that includes a propellant material as noted above. In other examples, the perforator charge 112 can be implemented without a propellant material.

The perforator charge 112 includes an outer case 502 that acts as a containment vessel designed to hold the detonation force of the explosion of the perforator charge 112 for a length of time to allow for a perforating jet to form. The outer case 502 can be formed of a metal, such as steel, or some other material. A main explosive 504 is contained inside the outer case 502. The main explosive 504 is sandwiched between the inner wall of the outer case 502 and a surface of a liner 506.

In some examples, the liner 506 is generally conically shaped. As a result of the general conical shape of the liner 506, the main explosive 504 is also generally conically shaped between an inner wall of the outer case 502 and the liner 506. In other examples, the liner 506 can be generally bowl-shaped or have a parabolic shape.

In examples according to FIG. 5, a rear portion of the outer case 502 has an opening 508, which can be in the form of a semi-circular slot or a slot having another shape. The opening 508 allows an end portion 510 of the main explosive 504 to be ballistically contacted to a primary explosive, such as the detonating cord 114 shown in FIG. 1.

In some examples, a retaining element 512 is attached (e.g. glued, welded, or otherwise attached) to the outer case 502. The retaining element 512 can be a retaining wire, for example, which is bendable for holding the detonating cord 114 against the rear portion 510 of the main explosive 504. In other examples, the retaining element 512 can be another type of retaining element, or alternatively, the retaining element 512 can be omitted.

According to some embodiments, the perforator charge 112 further has an energetic material 514, which is placed at a front portion of the perforator charge 112. The “front portion” of the perforator charge 112 is the portion of the perforator charge 112 through which the perforating jet extends upon detonation of the perforator charge 112. Stated differently, the “front portion” of the perforator charge 112 is at the front opening of the outer case 502, through which the perforating jet passes.

The energetic material 514 is generally a discrete segment formed of the energetic material that is placed at the front portion of the perforator charge 112. A “discrete segment” of energetic material can refer to any layer, piece, or other amount of the energetic material that has a predefined extent such that the energetic material does not surround an outer surface 503 of the outer cover 502. In some examples, the discrete segment of energetic material 514 does not contact any part of the outer surface 503 of the outer cover 502.

The energetic material 514 is retained to the outer case 502 of the perforator charge 112 using a retaining structure that is attached to the outer case 502. In some implementations, the retaining structure can be a retaining shell (or retaining cap) 516 that covers the discrete segment of energetic material 514. The retaining shell 516 has a receiving chamber 518 in which the energetic material 514 is positioned. The retaining shell 516 has a protruding portion 520 that extends into an inner opening of the energetic material 514 The retaining shell 516 is attached to the outer case 502 (at 517). The attachment can be a threaded connection between the retaining shell 516 and the outer case 502. Alternatively, the retaining shell 516 can be attached to the outer case 502 using another type of attachment mechanism, such as by use of a screw, a rivet, glue, and so forth.

In examples according to FIG. 5, the retaining shell 516 has a protruding portion 220 that extends into an inner opening 515 (shown in FIG. 6) of the energetic material 514. FIG. 6 is a sectional view of the energetic material 514, which is generally ring-shaped and has the inner opening 515 formed in the energetic material 514. The energetic material 514 is “generally” ring-shaped in that the energetic material 514 has a shape resembling a ring—note that manufacturing or design tolerances can cause the energetic material 514 to not have an exact ring shape.

In different implementations, rather than providing the generally ring-shaped energetic material 514 that has the inner opening 515, a generally disk-shaped energetic material can be provided, which does not include the inner opening 515 in an inner portion (e.g. center) of the energetic material. In other examples, instead of providing an energetic material that is generally circular in cross section, energetic materials having other shapes can be employed.

As further shown in FIG. 5, the perforator charge 112 can include a shock attenuator 522 positioned between the energetic material 514 and the main explosive 504. The shock attenuator 522 can be a layer of shock attenuation material, such as a polymer, plastic, a material containing air spaces or other voids, foam, cork, or any other metallic or non-metallic material of relatively low density. The shock attenuator 522 in some examples can also be generally ring-shaped. The shock attenuator 522 is arranged to cause a delay between the detonation of the explosive 504 and activation of the energetic material 514. This delay allows a perforation tunnel to first be formed by the perforating jet produced by the perforator charge 112, after which activation of the energetic material 514 creates an energy wave for enlarging the perforation tunnel, creating fractures, and/or removing crushed zone damage.

In other implementations, the shock attenuator 522 can be omitted.

In operation, the detonating cord 114 of FIG. 1 is initiated, which causes detonation of the main explosive 504 in the perforator charge 112. Detonation of the main explosive 504 creates a detonation wave that causes the liner 506 to collapse under the detonation force of the main explosive 504. Material from the collapsed liner 506 forms a perforating jet which shoots out through the front opening of the outer case 502 and towards the surrounding structure, which can include the casing/liner 104 and the surrounding subterranean formation.

The collapse of the liner 506 under the detonation force starts near an apex portion 524 of the liner 506, and proceeds to near the base portion 526 of the liner 506. The tip of the perforating jet produced from collapse of the liner 506 is formed by the apex portion 524 of the liner 506, while the tail of the perforating jet is formed by the base portion 526 of the liner 506.

In implementations where the energetic material 514 is generally ring-shaped, the perforating jet extends through the opening 515 (FIG. 6) of the energetic material 514. After some amount of delay caused by the shock attenuator 522, the energetic material 514 is activated, which produces an energy wave. Activation of the energetic material 514 is caused by the detonation wave of the main explosive 504.

FIG. 7 illustrates a process of assembling a perforating apparatus according to some implementations. The process of FIG. 7 can be performed by a manufacturer or by any other entity that is able to assemble a perforating apparatus. The process provides (at 702) a carrier (e.g. loading tube 110), and explosive devices (e.g. perforator charges 112) are mounted (at 704) to the carrier. Propellant cells (e.g. 220) are arranged (at 706) among the explosive devices. In addition, a propellant sleeve (e.g. 224 or 226) is provided (at 708) around the carrier, the sleeve being formed of an energetic material, and the sleeve and energetic cells for activation in response to detonation of the explosive devices.

In the foregoing description, numerous details are set forth to provide an understanding of the subject disclosed herein. However, implementations may be practiced without some or all of these details. Other implementations may include modifications and variations from the details discussed above. It is intended that the appended claims cover such modifications and variations. 

What is claimed is:
 1. A perforating apparatus comprising: a carrier; explosive devices mounted to the carrier; energetic cells arranged among the explosive devices; and a sleeve defining an inner chamber that receives at least a portion of the carrier, the sleeve being formed of an energetic material, the energetic cells and the sleeve for activation in response to detonation of the explosive devices.
 2. The perforating apparatus of claim 1, wherein the carrier is a loading tube containing the explosive devices and the energetic cells.
 3. The perforating apparatus of claim 1, wherein the explosive devices include perforator charges.
 4. The perforating apparatus of claim 3, wherein at least one of the perforator charges includes: a case; an explosive inside the case; a liner to be collapsed by detonation of the explosive to form a perforating jet; and a member formed of an energetic material for activation in response to detonation of the explosive, wherein the member is retained to the case.
 5. The perforating apparatus of claim 1, further comprising: an outer housing in which the carrier is contained; and a second sleeve formed of an energetic material around an outer surface of the outer housing.
 6. The perforating apparatus of claim 1, wherein the energetic material is selected from the group consisting of a propellant, a high explosive, a gun powder, a combustible metallic powder, thermite, or any combination thereof.
 7. The perforating apparatus of claim 1, comprising a plurality of sections, wherein a first of the sections includes the carrier, explosive devices, and sleeve, and wherein a second of the sections connected to the first section includes a charge formed of an energetic material.
 8. The perforating apparatus of claim 1, wherein the sleeve includes openings corresponding to positions of the explosive devices mounted to the carrier.
 9. The perforating apparatus of claim 8, wherein the sleeve further includes grooves interconnecting the openings, and the perforating apparatus further comprises a detonating cord arranged along the grooves, wherein the detonating cord is ballistically connected to the explosive devices.
 10. A modular sleeve comprising: a tubular structure defining an inner chamber to receive a carrier mounted with explosive devices, the tubular structure formed of an energetic material for activation by detonation of the explosive devices, the tubular structure including openings corresponding to positions of the explosive devices mounted to the carrier.
 11. The modular sleeve of claim 10, wherein the tubular structure further includes grooves interconnecting the openings, the grooves to receive a detonating cord for ballistic coupling to the explosive devices.
 12. The modular sleeve of claim 11, wherein the grooves extend generally along a spiral path along the tubular structure.
 13. The modular sleeve of claim 10, wherein the energetic material is selected from the group consisting of a propellant, a high explosive, a gun powder, a combustible metallic powder, thermite, or any combination thereof.
 14. A method of assembling a perforating apparatus, comprising: providing a carrier; mounting explosive devices to the carrier; arranging energetic cells among the explosive devices; and providing a sleeve around the carrier, the sleeve being formed of an energetic material, and the sleeve and energetic cells for activation in response to detonation of the explosive devices.
 15. The method of claim 14, wherein providing the carrier comprises providing a loading tube containing the explosive devices and energetic cells.
 16. The method of claim 14, further comprising providing the carrier inside an outer housing of the perforating apparatus.
 17. The method of claim 16, further comprising providing a second sleeve around the outer housing, the second sleeve formed of an energetic material for activation in response to detonation of the explosive devices.
 18. The method of claim 14, wherein mounting the explosive devices comprises mounting perforator charges. 